1. Field of the Invention
The present invention relates to a liquid ejection head configured to eject liquid to record information on a recording medium by the ink-jet method.
2. Description of the Related Art
A liquid ejection head is known that has a filter disposed between a passage and an ink supply port in order to prevent a clogging of an ejection orifice with foreign matter, such as dust, contained in ink. One known example of a recording head having a filter is illustrated in FIGS. 6A to 6C. FIG. 6A illustrates nozzles and their adjacent areas of the recording head; FIG. 6B is a cross-sectional view taken along the line VIB-VIB in FIG. 6A; and FIG. 6C is a cross-sectional view taken along the line VIC-VIC in FIG. 6A.
The recording head of this example has a configuration in which a filter 301 having a substantially rectangular opening with the shorter side L1 and the longer side L2 and a substantially circular ejection orifice 100 for allowing ink to be ejected therethrough with the diameter D1 (=D2).
There is a desire for smaller droplets to be ejected and higher resolution in recording in order to achieve further higher image quality. To attain the desire, it is necessary to reduce the size of an ejection orifice of a recording head and increase the resolution of a nozzle array. In this case, the distance between nozzles is reduced and thus the width of a nozzle wall forming a partition between the nozzles is reduced, so a problem arises in that adhesion to a substrate cannot be sufficiently maintained. One known approach to addressing this problem is a liquid ejection head that has a substantially oval ejection orifice, as illustrated in FIGS. 7A to 7C. The recording head of the example illustrated in FIGS. 7A to 7C has a filter having a substantially rectangular opening with the shorter side L1 and the longer side L2 and a substantially oval ejection orifice for allowing ink to be ejected therethrough with the minor diameter D1 and the major diameter D2.
Another known approach to increasing the resolution of a nozzle array is a technique for maintaining a sufficient clearance between nozzles and a sufficient thickness of each nozzle wall by the use of an arrangement of staggered pressure chambers, as illustrated in Japanese Patent Laid-Open No. 2005-1379 and No. 2006-315395.
With a configuration that satisfies the relations D1>L1, D1>L2, D2>L1, and D2>L2, as illustrated in FIGS. 6A to 6C, an entry of foreign matter into a pressure chamber can be reduced. However, a problem remains in that the ink supply performance from a liquid chamber communicating with a supply port to the pressure chamber deteriorates.
Here, a case is discussed where the size of an ejection orifice is reduced to increase the resolution of a nozzle in order to fulfill the desire for higher image quality. With the configuration that satisfies the relations D1>L1, D1>L2, D2>L1, and D2>L2, as illustrated in FIGS. 6A to 6C, D1 and D2 are reduced with a reduction in the size of the ejection orifice. From the above relations, this results in a reduction in L1 and L2, so the ink supply performance from the liquid chamber to the nozzles deteriorates. With the aim of solving this problem, the liquid ejection head illustrated in FIGS. 7A to 7C has a configuration that satisfies the relations L1>D1 and L2>D2. Unfortunately, with this configuration, if foreign matter enters the pressure chamber, it is difficult to discharge the foreign matter through the ejection orifice to the outside and it may cause a clogging of the ejection orifice.
With the configuration using staggered pressure chambers, a problem arises in that the ink supply performance to a pressure chamber having a longer distance from the ink supply port deteriorates. Therefore, even with this configuration using the staggered formation, it is desired to improve the ink supply performance.